RE: How to Verify Git GPG Signed Downloads?

From: Jason Pyeron <jpyeron@pdinc.us>
Date: Jan 24, 2021, 17:57 UTC
Message-ID: <022601d6f27a$58a97200$09fc5600$@pdinc.us>
In-Reply-To: <B6DFB74D-A722-4DBD-A4B2-562604B21CCB@alchemists.io>

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> From: Brooke Kuhlmann
> Sent: Sunday, January 24, 2021 11:49 AM
> 
> Hello, I'm trying to figure out how to obtain the public key used to 
> encrypt

Do you mean sign?

> the Git file
> downloads. I put together a gist that explains the problem and question in detail here:
> 
> https://gist.github.com/bkuhlmann/684b74d25d83d52df8d0caeb6219aa15

Please don’t post links to questions, pasting your content inline here:

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> Problem
> When attempting to download a Git version, it would be nice to verify the signature of the download by running the following:
>
> curl --remote-name https://mirrors.edge.kernel.org/pub/software/scm/git/git-2.30.0.tar.gz
> curl --remote-name https://mirrors.edge.kernel.org/pub/software/scm/git/git-2.30.0.tar.sign
> gpg --verify git-2.30.0.tar.sign git-2.30.0.tar.gz
> Only problem is that the last line of the above throws the following error:
>
> gpg: Signature made Sun Dec 27 23:12:30 2020 MST
> gpg:                using RSA key E1F036B1FEE7221FC778ECEFB0B5E88696AFE6CB
> gpg: Can't check signature: No public key
> I tried using the following solutions to no avail:

$ gpg --recv-keys 96AFE6CB gpg: requesting key 96AFE6CB from hkp server keys.gnupg.net gpg: key 713660A7: "Junio C Hamano <gitster@pobox.com>" 59 new signatures gpg: key 713660A7: "Junio C Hamano <gitster@pobox.com>" 2 new subkeys gpg: no ultimately trusted keys found gpg: Total number processed: 1 gpg: new subkeys: 2 gpg: new signatures: 59

$ gpg --verify -v git-2.30.0.tar.sign git-2.30.0.tar.gz gpg: Signature made Mon Dec 28 01:12:30 2020 EST using RSA key ID 96AFE6CB gpg: NOTE: signature key 96AFE6CB expired Sun Jul 26 13:41:24 2020 EDT gpg: NOTE: signature key B3F7CAC9 expired Sun Jul 26 13:41:42 2020 EDT gpg: using subkey 96AFE6CB instead of primary key 713660A7 gpg: NOTE: signature key 96AFE6CB expired Sun Jul 26 13:41:24 2020 EDT gpg: NOTE: signature key 96AFE6CB expired Sun Jul 26 13:41:24 2020 EDT gpg: NOTE: signature key B3F7CAC9 expired Sun Jul 26 13:41:42 2020 EDT gpg: using PGP trust model gpg: BAD signature from "Junio C Hamano <gitster@pobox.com>" gpg: binary signature, digest algorithm SHA256

$ gpg --list-keys -v 96AFE6CB gpg: using PGP trust model gpg: NOTE: signature key 96AFE6CB expired Sun Jul 26 13:41:24 2020 EDT gpg: NOTE: signature key B3F7CAC9 expired Sun Jul 26 13:41:42 2020 EDT pub 4096R/713660A7 2011-10-01 uid Junio C Hamano <gitster@pobox.com> uid Junio C Hamano <junio@pobox.com> uid Junio C Hamano <jch@google.com> sub 4096R/96AFE6CB 2011-10-03 [expired: 2020-07-26] sub 4096R/833262C4 2011-10-01 sub 4096R/B3F7CAC9 2014-09-20 [expired: 2020-07-26]

It is possible that Junio forgot to push his refreshed public key.

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>
> gpg --locate-keys torvalds@kernel.org gregkh@kernel.org committer@example.com discord@example.net gitster@pobox.com
> gpg --import <file> # <= Need a file to import but where does one obtain the public key?
> I also tried importing only the public keys from the Git repository via the following files without any luck either:
>
> t/lib-gpg/keyring.gpg
> contrib/credential/netrc/test.git-config-gpg
> contrib/credential/netrc/test.netrc.gpg
> contrib/credential/netrc/test.command-option-gpg
> Question
> How does one figure out how to obtain the public keys for which the Git downloads were signed?
> 
> If anyone has any advice on how to make this possible, it would be greatly appreciated.
> 
> Thanks,
> Brooke
>